A report by the Gurgaon district administration on water bodies, prepared after collating data from three sources, has thrown up varying figures on the number of water bodies in the city at different times.

The report was prepared on the basis of satellite imagery of 2011-’12, which showed 647 water bodies in Gurgaon, maps issued by the Survey of India (SOI) in 1976, which pegged the number of water bodies at 519 and the state’s revenue records of 1956, according to which the total number of water bodies in the city stands at 640.

After examining the findings of the three data sources, experts listed by 123 water bodies that had been mentioned by all three sources.

The report by the Gurgaon administration is the result of a year-long survey in 2016 to identify water resources in the city. It was submitted to the National Green Tribunal last month.

The report mentions that while some water bodies dried up, some new ones sprang up in the city.

After studying the report, the NGT on Monday directed the Haryana government to preserve all water bodies in Gurgaon district, irrespective of their ownership status. This directive comes at a time when the green tribunal is hearing a petition filed by Lt. Col. (retd) Sarvadaman Singh Oberoi, seeking directions from the NGT to preserve and protect dying water bodies in the city.

The report points out that several water bodies, which were mentioned in the revenue records of 1956 and the SOI maps in 1976, did not figure in the preliminary assessment of the satellite imagery of 2011-’12. The petitioner claimed that a number of water bodies found in the satellite imagery weren’t notified as such in the revenue records.

The report further states that around 128 water resources in the city, which found mention in the revenue records of 1956 and also showed up in the satellite imagery of 2011-’12, did not feature in the SOI maps in 1976.

“The number (of water bodies) needs to be verified. The difference in the number of water bodies listed by the three data sources could well be attributed to the difference in scale of the sources,” Chetan Agarwal, an environment analyst who was part of the survey, said.

The NGT also asked the petitioner to examine the report on the status of water bodies in the city.

“There is an urgent need to preserve water bodies in the region, as it has been listed in the ‘dark zone’ (area where the groundwater level has dropped alarmingly) by Central Groundwater Authority in 2008. The situation is grim and the government should wake up before it’s too late,” Oberoi said.